1. Section 5.8 Exponential Growth and Decay Models; Newton’s Law; Logistic Growth and Decay Models

5. A colony of bacteria grows according to the law of uninhibited growth according to the function where N is measured in grams and t is measure in days.

6. (a) If N is the number of cells and t is the time in hours, express N as a function of t. (b) If the number of bacteria doubles in 2 hours, find the function that gives the number of cells in the culture. (c) How long will it take for the size of the colony to triple? (d) How long will it take for the population to double a second time (that is increase four times)? A colony of bacteria increases according to the law of uninhibited growth.

12. A cake is heated to 350°F and is then allowed to cool in a room whose air temperature is 70°F. (a)If the temperature of the cake is 300°F after 5 minutes, when will its temperature be 200°F? Use u(5) = 300 to find k.

13. A cake is heated to 350°F and is then allowed to cool in a room whose air temperature is 70°F. (b)Determine the elapsed time before the temperature of the cake is 100°F. (c)What do you notice about the temperature as time passes?